Apparatus for treating of steel or other metals, especially for continuous casting

ABSTRACT

Apparatus by which molten steel or other metal is deslagged and the air and other gasses absorbed by the hot metal during production are exhausted preparatory to the casting process and is especially adapted for use with a continuous casting process.

United States Patent lnventor llelmut Lenne Dusseldorf, Germany Appl. No. 760,567

Filed Sept. 18, 1968 Patented Jan. 26, 1971 Assignee Klockner-Werke A G Duisburg, Germany Priority Sept. 28, 1967 Germany APPARATUS FOR TREATING OF STEEL OR OTHER METALS, ESPECIALLY FOR CONTINUOUS CASTING 7 Claims, 2 Drawing Figs.

11.8. CI 266/34, 164/63, 164/257, 164/281 Int. Cl C21c 7/10, 322d 27/16 Field of Search 266/34V; 164/63, 253, 254, 256, 257, 258, 281; 103/1M, 103MP [56] References Cited UNITED STATES PATENTS 2,140,607 12/1938 Thompson 266/34(V)UX 3,263,283 8/1966 Allard 164/49 3,310,850 3/1967 Armbruster 164/254X 3,321,300 5/1967 Womer 266/34X FOREIGN PATENTS I 1,001,134 8/1965 Great Britain 164/63 Primary Examin erJ Spencer Overholser Assistant Examiner.lohn E. Roethel Attorneys-Kenwood Ross and Chester E. F lavin ABSTRACT: Apparatus by which molten steel or other metal is deslagged and the air and other gasses absorbed by the hot metal during production are exhausted preparatory to the casting process and is especially adapted for use with a continuous casting process.

PATENTEU M26 I97] 3,558,121

SHEET 1 OF 2 HELMUT LENNE BY )Qnwvd @0144! mafia/m Y ATTORNEYS.

PATENIED M26191: 3,558,121

SHEET 2 OF 2 Jnren/ozy HELMUT LENNE Wk/M4690 M /immgizwz ATTORNEYS.

APPARATUS FOR TREATING OF STEEL OR OTHER METALS, ESPECIALLY FOR CONTINUOUS CASTING BACKGROUND OF THE INVENTION 1. Field of the Invention The invention relates to a method and apparatus by which the molten metal is deslagged and theair or other gas is exhausted preparatory to the pouring of the molten metal into the casting means. Use hereof in a continuous casting process is most advantageous because of the need for continuous degassing, the continuous casting being coordinated with the continuous degassing so that there is no interruption in the continuity. It is to be explained, however, that the method and the apparatus will serve other casting procedures as well.

2. Description of the Prior Art In foundry technology, different methods and apparatus for the degassification of metals, prior to or during their casting, are known, but each suffers from the disadvantage that continuous degassing is not permitted. After the ladle has been discharged, the vacuum vessel normally employed is sealed and evacuated. Too, sufficient separation of the slag is not allowed. Also, slag may be drawn out and scrap produced, if the level of the metal in the vacuum apparatus is low. This risk arises particularly during the inflow of the metal into the pan, a current being established by which slag is drawn and distributed in the melt. If the level of the molten metal is high, these prior art methods do not allow rapid degassing for the reason that, in relation to the total volume of metal, only a small surface is available from which the gas can escape. Too, valuable metal is entrained by the overflow, if the level of the molten metal is too high.

A combined casting jet and surface degassing method does not allow a simple and quick degassing because of the necessary sealing at the pan hanging in the crane. Too, it is difficult to tighten the filler socket during pan removal. The connection of the sealing elements between the pan and the vacuum vessel must be accomplished under conditions of intense heat, requiring precise crane travel and endangering the foundry operator. Furthermore, a double degassing procedure is made necessary.

SUMMARY OF THE INVENTION The slag is first separated from the molten melt from without a degassing plant and preliminary to the degassing procedure for the well recognized purpose of avoiding the inclusion of slag in the casting process.

Deslagging is also performed within the degassing chamber and during the degassing operation, although preferentially and as above stated, slag separating ensues preliminary to the degassing operation, it being easier then to remove such than during degassing. Slag, within the degassing chamber, has a tendency to form a film over the molten metal and the gas has difficulty in escaping due to the low pressure available in the degassing chamber.

The molten metal is led through a deslagging device and thence into a collector.

The melt is sucked out of the collector through a collector tube and charged into a degassing chamber or plant, which chamber is disposed upon a variable incline so as to allow full discharge of the melt therefrom as desired but more importantly to accommodate to a varying in the height of the metal column in the collector tube so as to control the flow volume through the degassing chamber. A further purpose of the inclining means is to provide for the emptying of a collecting groove within the degassing chamber.

Within the degassing plant, the melt is first charged into a collecting groove at one extremity of a bottom wall and then flows outwardly from that collecting groove as a thinly spread flow stream for distribution over the width of the bottom wall surface, the groove extending transversely of the chamber so as to insure even distribution over the bottom wall width. The degassing plant being inclined, with the collector groove located at the top of the incline, the spreading action over the bottom wall is easily accomplished.

Slag entering the degassing plant from the collector is collected in the collecting groove.

The melt flows over the bottom wall toward an outflow groove at the opposite end of the bottom wall.

A variable suction means communicates with the degassing chamber for purposes of controlling the melt flow therethrough and for quickly evacuating the chamber of the gases so that the quantity of flow with respect to unit of time may be greatly accelerated.

The melt is conducted through the bottom of the outflow groove into an outflow discharge conduit communicating therewith, in which outflow discharge conduit, a flow governor is provided for regulating flow therethrough.

Also within the outflow discharge conduit, a diaphragm is provided for closing off passage of the melt therethrough, whereby degassing chamber evacuation is attained.

The melt flows from the outflow discharge conduit to a distributing chamber.

In an alternate form, the degassing chamber is constructed to define a bottom wall which takes the form of a climbing member along which the molten metal may be progressively transported upwardly by means of an electromagnetic device cooperant with the bottom wall, while simultaneously the slag is allowed to run downwardly into a channel adjacent the bottom wall.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional elevational view through the apparatus of the invention, whereby the molten metal runs over an inclined bottom by its own gravity; and

FIG. 2 is a sectional elevational view through a modified form of the apparatus showing the molten metal being transported along the inclined bottom by means of an electromagnetic device.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the FIG. 1 exemplification, the molten metal is shown as being delivered first to a slag separator 2 preliminary to passage through a degassing chamber or plant 7 for the purpose of allowing removal of the slag from the melt before degassing and before passage to the particular casting process being served by the invention.

Slag separator 2 comprises a tank provided with a plurality of spaced vertically-depending walls 1 therewithin, such walls serving to minimize circulation within the separator.

For purposes of collecting and removing the slag, it is necessary that currents, especially at the outflow side, be held to an absolute minimum so that the slag, having a lower specific gravity than the molten metal, and being free of circulatory effects, may freely rise to the surface of the molten metal.

The slag is collected on the surface of the molten metal between walls 1, especially in the last chamber, where there is nearly no more current caused by the entering jet. The slag may be taken off from the surface of the molten metal from time to time as by skimming off or it may flow out continuously through a pipe or channel or the like.

The deslagged molten metal is delivered from the slag separator to a collector 3 disposed therebelow, the collector being provided with an hydraulic elevating member 4 for its raising or lowering.

Additional slag may form within the collector and may be,

' here again, allowed to swim on the surface of the molten metal therein due to its lower specific gravity.

Elevating member 4 services to raise or lower the collector relative to a sucking or collector pipe 5 which sucking pipe has a lower extremity disposed within the supply of molten metal in the collector. By its means, the molten metal is continuously withdrawn from the collector and discharged into a degassing chamber of plant 7 next to be described.

It is desired to suck the molten metal into the degassing chamber, and also to regulate the sucked volume by varying the height of the metal melt column in sucking pipe 5 by elevating member 4, thereby taking advantage of the statical pressure, the pressure of ambient air on the surface of the metal in the collector being higher than the pressure in the degassing chamber. Furthermore, by sucking the molten metal, there is no danger of surrounding air bleeding into the degassing chamber.

The raising of collector 3 by elevator 4 serves to vary the metal column in sucking pipe 5 and thereby to regulate the flowing volume. In case of a small pressure difference between the degassing chamber and the surrounding air, collector 3 will be elevated and in case of a high pressure difference, it will be lowered. The suction action is created by the pressure difference and the height of the metal column in the sucking pipe as controlled by elevating or lowering the collector.

Degassing chamber 7 comprises an enclosed area defined by a bottom wall 8, a top wall spaced thereabove, and spaced opposite side and end walls.

The degassing chamber is mechanically inclinable by means of an elevating member 18 disposed beneath and supporting bottom wall 8 at the inboard end thereof to allow flow of the melt by gravity.

At the opposite ends of bottom wall 8, grooves are provided which extend transversely of the degassing chamber.

The melt is first charged into a V-shaped collecting groove 6 which is disposed below the plane of and at the inboard extremity of the bottom wall. At the lower opposite outboard end of the bottom wall, an outflow groove 9 is provided, similarly disposed below the plane of the bottom wall.

Upon inclination of the degassing plant, the melt is caused to overflow from collecting groove 6 as a thin spread and is distributed over the entire width of bottom wall 8, the groove extending transversely of the chamber so as to insure the desired even distribution of the stream over the entirety of the bottom wall width.

With the collector groove being positioned at what constitutes the top of the incline, when the inboard end of the degassing plant is elevated above the horizontal plane of its outboard end, the spreading action is achieved.

The molten metal is continuously sucked into the degassing chamber and is continuously led over bottom wall 8, the continuous operation being achieved by the height of the melt column in pipe 5 as controlled by elevating or lowering collector 3.

The melt runs over the bottom wall in a stream of some several centimeters in thickness so that the surface area of the melt in relation to the volume of the flowing melt is exceedingly large, all to the end that optimum degassing is achieved.

The spreading action allows the melt to be degassed as it flows toward and into outflow groove 9 at the opposite lower extremity of the bottom wall.

By inclining the degassing chamber too much, the molten metal will run too fast for getting a high degree of degassing, because there would be not enough time available for the degassing. The degree of incline therefore depends on the degree of the needed or wanted degassing.

Groove 6 is emptied by tilting the whole degassing chamber with elevating means 18 and tilting joint 17.

The top wall of the degassing chamber supports therebelow a plurality of heating rods 11 for compensating for the inescapable heat losses within the chamber.

An external variable suction pump means (not shown) is provided which communicates through a conduit with the degassing chamber for purposes of drawing the melt into the degassing chamber and degassing the melt and evacuating the chamber of the unwanted gases and controlling the rate of flow of the melt therethrough.

The exhausting procedure is carried out quickly so that the quantity of flow with respect to unit of time may be greatly accelerated.

The melt is conducted through the bottom of outflow 9 groove into an outflow discharge conduit 12 communicating therewith.

v Within the outflow discharge conduit, a flow governor 13 is provided for regulating the flow of melt therethrough.

Also within the outflow discharge conduit, a diaphragm 14 is provided for initially closing off the passage as evacuation of the degassing chamber is first achieved.

The melt flowed into groove 9 is discharged therefrom into outflow discharge conduit 12 from which it is flowed to a distributing chamber 15 disposed vertically therebelow, which chamber is filled with a nonreacting gas for insuring that the degassed melt will not take gas again.

From distributing chamber 15, a plurality of pipes 16 lead therefrom for the passage of the deslagged and degassed melt to the subsequent continuous casting apparatus (not shown).

At each component, deslagging means, collector means, degassing means, outflow discharge conduit, and distributing chamber, liquid level control means 20, see FIG. 2, may be provided in order to control the level of the metal therewithin individually and collectively.

As shown in FIG. 2, three such instruments 20 are arranged at collector 3', grooves 6' and 9 and distributor 15'. They indicate if the level of the molten metal lies in the corresponding height. These instruments may be ultrasonic or isotope devices.

lf there is an interruption in the continuous casting plant, it is necessary to control the rate of flow through outflow discharge conduit 12, as degassing and casting should work together in a continuous process, i.e. it is necessary to lead metal to the casting plant in such quantity and at such rate as the plant requires.

In the HO. 2 exemplification, the alternate form, the slag separator of FIG. 1 is not shown but it will be understood that, preferentially, it is used. The molten metal is shown as being delivered first to a collector 3 provided with a hydraulic elevating member 4' for raising or lowering the collector relative to a sucking pipe 5 which has a lower extremity disposed within the supply of molten metal in collector 3. By means of the sucking pipe, the metal is withdrawn from the collector and discharged into the degassing chamber or plant.

Degassing chamber 7 comprises an enclosed area disposed in an inclined plane and defined by a bottom wall 8', a top wall spaced thereabove, and spaced opposite side and end walls.

Bottom wall 8' and the inboard-end wall cooperantly define a lowermost collecting groove 6' which extends transversely of the degassing chamber between the opposite side walls.

Bottom wall 8', being permanently inclined, defines a climbing member cooperantly with an electromagnetic device 19 disposed therebelow and thereadjacent so that the melt, first charged into the lower collecting groove, is able to be transported therefrom as a thin spread over and upwardly along the entire width of the bottom wall.

The melt is transported, by means of the electromagnetic device 19 upwardly along the bottom wall, while the slag is allowed to fall downwardly and into lowermost groove 6.

The spreading action allows the melt to be degassed as it flows upwardly toward and into an outflow groove 9 at the opposite extremity of the bottom wall, which outflow groove is disposed below the plane of the uppermost edge of the bottom wall.

The top wall of the degassing chamber supports therebelow a plurality of heating rods 11 to compensate for heat losses.

A variable suction pump means (not shown) is provided which communicates with the degassing chamber for purposes of withdrawing the melt into the chamber and controlling the flow therethrough and separating the gas from the molten metal.

The exhausting procedure here again is carried out expeditiously so that the quantity of flow with respect to unit of time may be greatly accelerated.

The melt runs upwardly of the bottom wall as a stream of several centimeters in thickness. Accordingly, the surface area of the melt in relation to the volume of the flowing melt is exceedingly large, all to the end that optimum degassing is achieved.

The melt passes over the outboard edge of bottom wall 8' and is allowed to flow downwardly into groove 9.

The melt is conducted through the bottom of outflow groove 9' into an outflow discharge conduit 12' communicating therewith.

Within the outflow discharge conduit, a flow governor 13' is provided for regulating the flow of melt therethrough.

Also within the outflow discharge conduit, a diaphragm 14' is provided for closing off passage of the melt therethrough whereby evacuation of the degassing chamber is attained.

The melt then flows from groove 9' and into outflow discharge conduit 12' and therefrom into a distributing chamber 15' disposed vertically therebelow, which chamber is filled with a nonreacting gas.

From distributor 15', a plurality of pipes 16 lead the melt therefrom to the casting apparatus (not shown).

I claim:

1. Apparatus for deslagging and degassing molten metal comprising:

a slag separator,

a collector,

an enclosed degassing chamber,

a distributing chamber, 7 Y

first conduit means affording communication between the slag separator and the collector,

second conduit means affording communication between the collector and the degassing chamber,

third conduit means affording communication between the degassing chamber and the distributing chamber,

the degassing chamber having a bottom wall which inclines upwardly from the collector to the distributing chamber and having a collecting groove at its lower end adjacent the second conduit means and an outflow groove at its upper end adjacent the third conduit means,

7 an electromagnetic climbing device associated with the bot tom wall of the degassing chamber,

the molten metal passing from the slag separator through the first conduit means to the collector and from the collector through the second conduit means to the collecting groove of the degassing chamber,

the melt being transported by the electromagnetic climbing device as a wide, thin spread along the inclined bottom wall of the degassing chamber to the outflow groove while the slag remains in the collecting groove, and

the melt passing from the outflow groove to the distributing chamber.

2. Apparatus according to claim 1, wherein the second conduit means comprises a suction pipe.

3. Apparatus according to claim 2, including means for raising and lowering the collector for effectively varying the flow of molten metal from the collector to the degassing chamber.

4. Apparatus according to claim 1, wherein the degassing chamber includes a top wall in spaced parallelism to the bottom wall.

5. Apparatus according to claim 4, including heating means associated with the top wall.

6. Apparatus according to claim 1, including a meltable diaphragm across the third conduit means.

7. Apparatus according to claim 1, including level indicators at the collector, at the collecting and outflow grooves of the degassing chamber and at the distributing chamber. 

2. Apparatus according to claim 1, wherein the second conduit means comprises a suction pipe.
 3. Apparatus according to claim 2, including means for raising and lowering the collector for effectively varying the flow of molten metal from the collector to the degassing chamber.
 4. Apparatus according to claim 1, wherein the degassing chamber includes a top wall in spaced parallelism to the bottom wall.
 5. Apparatus according to claim 4, including heating means associated with the top wall.
 6. Apparatus according to claim 1, including a meltable diaphragm across the third conduit means.
 7. Apparatus according to claim 1, including level indicators at the collector, at the collecting and outflow grooves of the degassing chamber and at the distributing chamber. 